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  • Using LINQ to map dynamically (or construct projections)

    - by CodeGrue
    I know I can map two object types with LINQ using a projection as so: var destModel = from m in sourceModel select new DestModelType {A = m.A, C = m.C, E = m.E} where class SourceModelType { string A {get; set;} string B {get; set;} string C {get; set;} string D {get; set;} string E {get; set;} } class DestModelType { string A {get; set;} string C {get; set;} string E {get; set;} } But what if I want to make something like a generic to do this, where I don't know specifically the two types I am dealing with. So it would walk the "Dest" type and match with the matching "Source" types.. is this possible? Also, to achieve deferred execution, I would want it just to return an IQueryable. For example: public IQueryable<TDest> ProjectionMap<TSource, TDest>(IQueryable<TSource> sourceModel) { // dynamically build the LINQ projection based on the properties in TDest // return the IQueryable containing the constructed projection } I know this is challenging, but I hope not impossible, because it will save me a bunch of explicit mapping work between models and viewmodels.

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  • LINQ-SQL Updating Multiple Rows in a single transaction

    - by RPM1984
    Hi guys, I need help re-factoring this legacy LINQ-SQL code which is generating around 100 update statements. I'll keep playing around with the best solution, but would appreciate some ideas/past experience with this issue. Here's my code: List<Foo> foos; int userId = 123; using (DataClassesDataContext db = new FooDatabase()) { foos = (from f in db.FooBars where f.UserId = userId select f).ToList(); foreach (FooBar fooBar in foos) { fooBar.IsFoo = false; } db.SubmitChanges() } Essentially i want to update the IsFoo field to false for all records that have a particular UserId value. Whats happening is the .ToList() is firing off a query to get all the FooBars for a particular user, then for each Foo object, its executing an UPDATE statement updating the IsFoo property. Can the above code be re-factored to one single UPDATE statement? Ideally, the only SQL i want fired is the below: UPDATE FooBars SET IsFoo = FALSE WHERE UserId = 123 EDIT Ok so looks like it cant be done without using db.ExecuteCommand. Grr...! What i'll probably end up doing is creating another extension method for the DLINQ namespace. Still require some hardcoding (ie writing "WHERE" and "UPDATE"), but at least it hides most of the implementation details away from the actual LINQ query syntax.

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  • Populate a tree from Hierarchical data using 1 LINQ statement

    - by Midhat
    Hi. I have set up this programming exercise. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class DataObject { public int ID { get; set; } public int ParentID { get; set; } public string Data { get; set; } public DataObject(int id, int pid, string data) { this.ID = id; this.ParentID = pid; this.Data = data; } } class TreeNode { public DataObject Data {get;set;} public List<DataObject> Children { get; set; } } class Program { static void Main(string[] args) { List<DataObject> data = new List<DataObject>(); data.Add(new DataObject(1, 0, "Item 1")); data.Add(new DataObject(2, 0, "Item 2")); data.Add(new DataObject(21, 2, "Item 2.1")); data.Add(new DataObject(22, 2, "Item 2.2")); data.Add(new DataObject(221, 22, "Item 2.2.1")); data.Add(new DataObject(3, 0, "Item 3")); } } } The desired output is a List of 3 treenodes, having items 1, 2 and 3. Item 2 will have a list of 2 dataobjects as its children member and so on. I have been trying to populate this tree (or rather a forest) using just 1 SLOC using LINQ. A simple group by gives me the desired data but the challenge is to organize it in TreeNode objects. Can someone give a hint or an impossibility result for this?

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  • LINQ to Entity: using Contains in the "select" portion throws unexpected error

    - by Chu
    I've got a LINQ query going against an Entity Framework object. Here's a summary of the query: //a list of my allies List<int> allianceMembers = new List<int>() { 1,5,10 }; //query for fleets in my area, including any allies (and mark them as such) var fleets = from af in FleetSource select new Fleet { fleetID = af.fleetID, fleetName = af.fleetName, isAllied = (allianceMembers.Contains(af.userID) ? true : false) }; Basically, what I'm doing is getting a set of fleets. The allianceMembers list contains INTs of all users who are allied with me. I want to set isAllied = true if the fleet's owner is part of that list, and false otherwise. When I do this, I am seeing an exception: "LINQ to Entities does not recognize the method 'Boolean Contains(Int32)' method" I can understand getting this error if I had used the contains in the where portion of the query, but why would I get it in the select? By this point I would assume the query would have executed and returned the results. This little ditty of code does nothing to constrain my data at all. Any tips on how else I can accomplish what I need to with setting the isAllied flag? Thanks

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  • Linq merging results

    - by glenneroo
    I'm working with a list within a list. This is how I'm currently searching: var tags = from fd in BigList from tag in fd.Tags where tag.Id == selectedTag.Id || tag.Id == ID.TIMESTAMP select new { fd.Name, tag.Id, tag.Value }; I then iterate over the result-set and remembering when Timestamp pops up for the next entry, needless to say this is sloppy and I'm positive there's a better way using Linq, I just can't seem to find the syntax. Here's some sample output (Id indicates what type of data is stored inside e.g. a timestamp): Name | Id | Value -----|----|---------- 0000 | 1 | <timestamp> 0000 | 2 | 1.2 ... 9999 | 1 | <timestamp> 9999 | 2 | 6.3 I need all instances where Id = selectedTag.Id. I just want 1 list with Name, Id, Value and Timestamp, but the problem is my above attempt returns 2 entries for every item (1 for timestamp and 1 for the value). Is there a way to do this using Linq? Preferably using query syntax! :)

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  • Object mapping with LINQ and SubSonic

    - by Jeremy Seekamp
    I'm building a small project with SubSonic 3.0.0.3 ActiveRecord and I'm running into an issue I can't seem to get past. Here is the LINQ query: var result = from r in Release.All() let i = Install.All().Count(x => x.ReleaseId == r.Id) where r.ProductId == productId select new ReleaseInfo { NumberOfInstalls = i, Release = new Release { Id = r.Id, ProductId = r.ProductId, ReleaseNumber = r.ReleaseNumber, RevisionNumber = r.RevisionNumber, ReleaseDate = r.ReleaseDate, ReleasedBy = r.ReleasedBy } }; The ReleaseInfo object is a custom class and looks like this: public class ReleaseInfo { public Release Release { get; set; } public int NumberOfInstalls { get; set; } } Release and Install are classes generated by SubSonic. When I do a watch on result, the Release property is null. If I make this a simpler query and watch result, the value is not null. var result = from r in Release.All() let i = Install.All().Count(x => x.ReleaseId == r.Id) where r.ProductId == productId select new Release { Id = r.Id, ProductId = r.ProductId, ReleaseNumber = r.ReleaseNumber, RevisionNumber = r.RevisionNumber, ReleaseDate = r.ReleaseDate, ReleasedBy = r.ReleasedBy }; Is this an issue with my LINQ query or a limitation of SubSonic?

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  • DuplicateKeyException in LINQ, but I've set auto increment and auto sync

    - by Fritos
    I'm getting a DuplicateKeyException error in my C# code. I've set Auto Generated = true, and Auto-Sync = OnInsert in my dbml. I'm not even touching the PK field in any manually written code (as seen below [My primary key field is actually called PK]). using (DeviceExerciseDataDataContext context = new DeviceExerciseDataDataContext()) { foreach(Data tgudData in data.Data) { tgd = new tableData(); tgd.FK = key; tgd.Time = tgudData.TimeStamp; tgd.Calories = Convert.ToInt32(tgudData.Calories); tgd.HeartRate = tgudData.AvgHr; tgd.BenchAngle = tgudData.Angle; tgd.WorkoutTarget = 0; tgd.Reps = tgudData.Reps; context.tableDatas.InsertOnSubmit(tgd); } context.SubmitChanges(); } This is the code for the column in the designer (columns are named PK and FK) [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_PK", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL", IsPrimaryKey=true, IsDbGenerated=true)] public int PK { get { return this._PK; } set { if ((this._PK != value)) { this.OnPKChanging(value); this.SendPropertyChanging(); this._PK = value; this.SendPropertyChanged("PK"); this.OnPKChanged(); } } } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_FK", DbType="Int")] public System.Nullable<int> FK { get { return this._FK; } set { if ((this._FK != value)) { this.OnFKChanging(value); this.SendPropertyChanging(); this._FK = value; this.SendPropertyChanged("FK"); this.OnFKChanged(); } } }

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  • compare two text files using linq?

    - by bala3569
    I have 4 text files in one folder and a pattern.txt to compare these text files..In pattern.txt i have insert update delete drop I need to compare this text file with those four text files and if these patterns matches any line in that text files i have to write those lines in another log file...i had read those files using linq..i need to compare those files and write in a text file with line number..here is my code var foldercontent = Directory.GetFiles(pathA) .Select(filename => File.ReadAllText(filename)) .Aggregate(new StringBuilder(), (sb, s) => sb.Append(s).Append(Environment.NewLine), sb => sb.ToString()); var pattern = File.ReadAllLines(pathB).Aggregate(new StringBuilder(), (sb, s) => sb.Append(s).Append(Environment.NewLine), sb => sb.ToString()); using (var dest = File.AppendText(Path.Combine(_logFolderPath, "log.txt"))) { //dest.WriteLine("LineNo : " + counter.ToString() + " : " + "" + line); } EDIT I have already used c# to compare two text files but i need this in linq while ((line = file.ReadLine()) != null) { if (line.IndexOf(line2, StringComparison.CurrentCultureIgnoreCase) != -1) { dest.WriteLine("LineNo : " + counter.ToString() + " : " + " " + line.TrimStart()); } counter++; } file.BaseStream.Seek(0, SeekOrigin.Begin); counter = 1;

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  • Getting a Specified Cast is not valid while importing data from Excel using Linq to SQL

    - by niceoneishere
    This is my second post. After learning from my first post how fantastic is to use Linq to SQL, I wanted to try to import data from a Excel sheet into my SQL database. First My Excel Sheet: it contains 4 columns namely ItemNo ItemSize ItemPrice UnitsSold I have a created a database table with the following fields table name ProductsSold Id int not null identity --with auto increment set to true ItemNo VarChar(10) not null ItemSize VarChar(4) not null ItemPrice Decimal(18,2) not null UnitsSold int not null Now I created a dal.dbml file based on my database and I am trying to import the data from excel sheet to db table using the code below. Everything is happening on click of a button. private const string forecast_query = "SELECT ItemNo, ItemSize, ItemPrice, UnitsSold FROM [Sheet1$]"; protected void btnUpload_Click(object sender, EventArgs e) { var importer = new LinqSqlModelImporter(); if (fileUpload.HasFile) { var uploadFile = new UploadFile(fileUpload.FileName); try { fileUpload.SaveAs(uploadFile.SavePath); if(File.Exists(uploadFile.SavePath)) { importer.SourceConnectionString = uploadFile.GetOleDbConnectionString(); importer.Import(forecast_query); gvDisplay.DataBind(); pnDisplay.Visible = true; } } catch (Exception ex) { Response.Write(ex.Source.ToString()); lblInfo.Text = ex.Message; } finally { uploadFile.DeleteFileNoException(); } } } // Now here is the code for LinqSqlModelImporter public class LinqSqlModelImporter : SqlImporter { public override void Import(string query) { // importing data using oledb command and inserting into db using LINQ to SQL using (var context = new WSDALDataContext()) { using (var myConnection = new OleDbConnection(base.SourceConnectionString)) using (var myCommand = new OleDbCommand(query, myConnection)) { myConnection.Open(); var myReader = myCommand.ExecuteReader(); while (myReader.Read()) { context.ProductsSolds.InsertOnSubmit(new ProductsSold() { ItemNo = myReader.GetString(0), ItemSize = myReader.GetString(1), ItemPrice = myReader.GetDecimal(2), UnitsSold = myReader.GetInt32(3) }); } } context.SubmitChanges(); } } } can someone please tell me where am I making the error or if I am missing something, but this is driving me nuts. When I debugged I am getting this error when casting from a number the value must be a number less than infinity I really appreciate it

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  • OrderBy Linq.Expression as parameter = (Of Func(Of T,IComparable)) to perform LinqToEntity is not working

    - by NicoJuicy
    I'd like to get this working: Call: (Count & Page are used for pagination, so Count = 20 and Page = 1 for example, for the first 20 values). Sorting should be by name LeverancierService.GetLeveranciers(Function(el) el.Name, Count, Page) Equivalent in c#: LeverancierService.GetLeveranciers(el= el.Name, Count, Page) Method that gives an error (parameters shown above): Public Overridable Function GetAllPaged(orderby As Expression(Of Func(Of T, IComparable)), ByVal Count As Integer, ByVal Page As Integer) As IEnumerable(Of T) Return dbset.OrderBy(orderby).Skip((Page - 1) * Count).Take(Count).ToList() End Function Already tried changing it to this, but it gives the same error: Public Overridable Function GetAllPaged(Of TOrderBy)(orderby As Expression(Of Func(Of T, TOrderBy)), ByVal Count As Integer, ByVal Page As Integer) As IEnumerable(Of T) Return dbset.OrderBy(orderby).Skip((Page - 1) * Count).Take(Count).ToList() End Function Error: Unable to cast the type 'System.String' to type 'System.IComparable'. LINQ to Entities only supports casting Entity Data Model primitive types. Any idea how to do this? Extra info: I'm in a DDD-layered application, so the parameter should stay the same as the called method is an overridden interface (eg. if i change this, i have to do this for 200 times or so, because it's in VB.Net and not in C# (= 1 change) ) I know there is a way to change the expression to a string and then use DLinq (= Dynamic Linq), but that's not how it should be.

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  • Linq to SQL duplicating entry when referencing FK

    - by Oscar
    Hi! I am still facing some problems when using LINQ-to-SQL. I am also looking for answers by myself, but this problem is so akward that I am having problems to find the right keywords to look for it. I have this code here: public CustomTask SaveTask(string token, CustomTask task) { TrackingDataContext dataConext = new TrackingDataContext(); //Check the token for security if (SessionTokenBase.Instance.ExistsToken(Convert.ToInt32(token)) == null) return null; //Populates the Task - the "real" Linq to SQL object Task t = new Task(); t.Title = task.Title; t.Description = task.Description; //****The next 4 lines are important**** if (task.Severity != null) t.Severity = task.Severity; else t.SeverityID = task.SeverityID; t.StateID = task.StateID; if (task.TeamMember != null) t.TeamMember = task.TeamMember; else t.ReporterID = task.ReporterID; if (task.ReporterTeam != null) t.Team = task.ReporterTeam; else t.ReporterTeamID = task.ReporterTeamID; //Saves/Updates the task dataConext.Tasks.InsertOnSubmit(t); dataConext.SubmitChanges(); task.ID = t.ID; return task; } The problem is that I am sending the ID of the severity, and then, when I get this situation: DB State before calling the method: ID Name 1 high 2 medium 3 low Call the method selecting "medium" as severity DB State after calling the method: ID Name 1 high 2 medium 3 low 4 medium The point is: -It identified that the ID was related to the Medium entry (and for this reason it could populate the "Name" Column correctly), but if duplicated this entry. The problem is: Why?!! Some explanation about the code: CustomTask is almost the same as Task, but I was having problems regarding serialization as can be seen here I don't want to send the Severity property populated because I want my message to be as small as possible. Could anyone clear to my, why it recognize the entry, but creates a new entry in the DB?

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  • Linq-to-XML explicit casting in a generic method

    - by vlad
    I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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  • LINQ to SQL - Insert yielding strange behavior.

    - by Isaac
    Hi, I'm trying to insert several newly created items to the database. I have a LINQ2SQL generated class called "Order". Inside order, there's a property called "OrderItems" which is also generated by LINQ2SQL and represents the Items of that Order. So far so good. The problem I'm having right now, is when I try to add more than one newly created OrderItem inside Order. I.E: Order o = orderWorker.GetById( 10 ); for( int i=0; i < 5; ++i ) { OrderItem oi =new OrderItem { Order = order, Price = 100, ShippingPrice = 100, ShippingMethod = ... }; o.OrderItems.Add( oi ); } context.SubmitChanges(); Unfortunately, only a single entity is being added. Yes, I checked the generated SQL by adding Context.Log = Console.Out, and yes, only one statement was created. Any clues? By the way I know I'm not using InsertOnSubmit, by the documentation says: You can explicitly request Inserts by using InsertOnSubmit. Alternatively, LINQ to SQL can infer Inserts by finding objects connected to one of the known objects that must be updated. For example, if you add an Untracked object to an EntitySet(TEntity) or set an EntityRef(TEntity) to an Untracked object, you make the Untracked object reachable by way of tracked objects in the graph. While processing SubmitChanges, LINQ to SQL traverses the tracked objects and discovers any reachable persistent objects that are not tracked. Such objects are candidates for insertion into the database. Thank you very much for your time.

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  • Strongly typed dynamic Linq sorting

    - by David
    I'm trying to build some code for dynamically sorting a Linq IQueryable<. The obvious way is here, which sorts a list using a string for the field name http://dvanderboom.wordpress.com/2008/12/19/dynamically-composing-linq-orderby-clauses/ However I want one change - compile time checking of field names, and the ability to use refactoring/Find All References to support later maintenance. That means I want to define the fields as f=f.Name, instead of as strings. For my specific use I want to encapsulate some code that would decide which of a list of named "OrderBy" expressions should be used based on user input, without writing different code every time. Here is the gist of what I've written: var list = from m Movies select m; // Get our list var sorter = list.GetSorter(...); // Pass in some global user settings object sorter.AddSort("NAME", m=m.Name); sorter.AddSort("YEAR", m=m.Year).ThenBy(m=m.Year); list = sorter.GetSortedList(); ... public class Sorter ... public static Sorter GetSorter(this IQueryable source, ...) The GetSortedList function determines which of the named sorts to use, which results in a List object, where each FieldData contains the MethodInfo and Type values of the fields passed in AddSort: public SorterItem AddSort(Func field) { MethodInfo ... = field.Method; Type ... = TypeOf(TKey); // Create item, add item to diction, add fields to item's List // The item has the ThenBy method, which just adds another field to the List } I'm not sure if there is a way to store the entire field object in a way that would allow it be returned later (it would be impossible to cast, since it is a generic type) Is there a way I could adapt the sample code, or come up with entirely new code, in order to sort using strongly typed field names after they have been stored in some container and retrieved (losing any generic type casting)

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  • Inefficient 'ANY' LINQ clause

    - by Focus
    I have a query that pulls back a user's "feed" which is essentially all of their activity. If the user is logged in the query will be filtered so that the feed not only includes all of the specified user's data, but also any of their friends. The database structure includes an Actions table that holds the user that created the action and a UserFriends table which holds any pairing of friends using a FrienderId and FriendeeId column which map to UserIds. I have set up my LINQ query and it works fine to pull back the data I want, however, I noticed that the query gets turned into X number of CASE clauses in profiler where X is the number of total Actions in the database. This will obviously be horrible when the database has a user base larger than just me and 3 test users. Here's the SQL query I'm trying to achieve: select * from [Action] a where a.UserId = 'GUID' OR a.UserId in (SELECT FriendeeId from UserFriends uf where uf.FrienderId = 'GUID') OR a.UserId in (SELECT FrienderId from UserFriends uf where uf.FriendeeId = 'GUID') This is what I currently have as my LINQ query. feed = feed.Where(o => o.User.UserKey == user.UserKey || db.Users.Any(u => u.UserFriends.Any(ufr => ufr.Friender.UserKey == user.UserKey && ufr.isApproved) || db.Users.Any(u2 => u2.UserFriends.Any(ufr => ufr.Friendee.UserKey == user.UserKey && ufr.isApproved) ))); This query creates this: http://pastebin.com/UQhT90wh That shows up X times in the profile trace, once for each Action in the table. What am I doing wrong? Is there any way to clean this up?

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  • LINQ: display results from empty lists

    - by Douglas H. M.
    I've created two entities (simplified) in C#: class Log { entries = new List<Entry>(); DateTime Date { get; set; } IList<Entry> entries { get; set; } } class Entry { DateTime ClockIn { get; set; } DateTime ClockOut { get; set; } } I am using the following code to initialize the objects: Log log1 = new Log() { Date = new DateTime(2010, 1, 1), }; log1.Entries.Add(new Entry() { ClockIn = new DateTime(0001, 1, 1, 9, 0, 0), ClockOut = new DateTime(0001, 1, 1, 12, 0, 0) }); Log log2 = new Log() { Date = new DateTime(2010, 2, 1), }; The method below is used to get the date logs: var query = from l in DB.GetLogs() from e in l.Entries orderby l.Date ascending select new { Date = l.Date, ClockIn = e.ClockIn, ClockOut = e.ClockOut, }; The result of the above LINQ query is: /* Date | Clock In | Clock Out 01/01/2010 | 09:00 | 12:00 */ My question is, what is the best way to rewrite the LINQ query above to include the results from the second object I created (Log2), since it has an empty list. In the other words, I would like to display all dates even if they don't have time values. The expected result would be: /* Date | Clock In | Clock Out 01/01/2010 | 09:00 | 12:00 02/01/2010 | | */

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  • Use Linq to SQL to generate sales report

    - by Richard Reddy
    I currently have the following code to generate a sales report over the last 30 days. I'd like to know if it would be possible to use linq to generate this report in one step instead of the rather basic loop I have here. For my requirement, every day needs to return a value to me so if there are no sales for any day then a 0 is returned. Any of the Sum linq examples out there don't explain how it would be possible to include a where filter so I am confused on how to get the total amount per day, or a 0 if no sales, for the last days I pass through. Thanks for your help, Rich //setup date ranges to use DateTime startDate = DateTime.Now.AddDays(-29); DateTime endDate = DateTime.Now.AddDays(1); TimeSpan startTS = new TimeSpan(0, 0, 0); TimeSpan endTS = new TimeSpan(23, 59, 59); using (var dc = new DataContext()) { //get database sales from 29 days ago at midnight to the end of today var salesForDay = dc.Orders.Where(b => b.OrderDateTime > Convert.ToDateTime(startDate.Date + startTS) && b.OrderDateTime <= Convert.ToDateTime(endDate.Date + endTS)); //loop through each day and sum up the total orders, if none then set to 0 while (startDate != endDate) { decimal totalSales = 0m; DateTime startDay = startDate.Date + startTS; DateTime endDay = startDate.Date + endTS; foreach (var sale in salesForDay.Where(b => b.OrderDateTime > startDay && b.OrderDateTime <= endDay)) { totalSales += (decimal)sale.OrderPrice; } Response.Write("From Date: " + startDay + " - To Date: " + endDay + ". Sales: " + String.Format("{0:0.00}", totalSales) + "<br>"); //move to next day startDate = startDate.AddDays(1); } }

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  • LINQ to SQL - database relationships won't update after submit

    - by Quantic Programming
    I have a Database with the tables Users and Uploads. The important columns are: Users -> UserID Uploads -> UploadID, UserID The primary key in the relationship is Users -> UserID and the foreign key is Uploads -> UserID. In LINQ to SQL, I do the following operations: Retrieve files var upload = new Upload(); upload.UserID = user.UserID; upload.UploadID = XXX; db.Uploads.InsertOnSubmit(upload) db.SubmitChanges(); If I do that and rerun the application (and the db object is re-built, of course) - if do something like this: foreach(var upload in user.Uploads) I get all the uploads with that user's ID. (like added in the previous example) The problem is, that my application, after adding an upload an submitting changes, doesn't update the user.Uploads collection. i.e - I don't get the newly added uploads. The user object is stored in the Session object. At first, I though that the LINQ to SQL Framework doesn't update the reference of the object, therefore I should simply "reset" the user object from a new SQL request. I mean this: Session["user"] = db.Users.Where(u => u.UserID == user.UserID).SingleOrDefault(); (Where user is the previous user) But it didn't help. Please note: After rerunning the application, user.Uploads does have the new upload! Did anyone experience this type of problem, or is it normal behavior? I am a newbie to this framework. I would gladly take any advice. Thank you!

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  • ASP.net MVC Linq-To-SQL Extended Class Field Binding

    - by user336858
    Hi there, The short version of this question is "Is there a way to get automatic View Object binding for fields defined in a partial class for a Linq-To-SQL generated class?" Apologies if it's been asked before. Example Suppose I have a typical MVC setup with the tables: Posts {PostID, ...} Categories {CategoryID, ...} A post can have more than one category, and a category can identify more than one post. Thus suppose further that I need an extra table: PostCategories {PostID, CategoryID, ...} This handles the many-to-many relationship between posts and categories. As far as I know, there's no way to do this in Linq-to-SQL right now so I have to shoehorn it in by adding a partial Postclass to the project to add that functionality. Something like: public partial class Post { public IEnumerable<Category> Categories{ get { ... } set { ... } } } So here's my question: If a user is accessing my MVC application front-end and begins editing a Post object, they might enter an invalid category. When the server recognizes the invalid input, the usual practice is to return the faulty object to the original view for re-editing along with some error messages. The fields in the edit page are re-populated with the provided values. However I don't know how to get this mechanism to work with the properties I created with the partial class as shown above. Any terminology, links, or tips you can provide would be tremendously helpful!

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  • Best ways to format LINQ queries.

    - by Aren B
    Before you ignore / vote-to-close this question, I consider this a valid question to ask because code clarity is an important topic of discussion, it's essential to writing maintainable code and I would greatly appreciate answers from those who have come across this before. I've recently run into this problem, LINQ queries can get pretty nasty real quick because of the large amount of nesting. Below are some examples of the differences in formatting that I've come up with (for the same relatively non-complex query) No Formatting var allInventory = system.InventorySources.Select(src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }).GroupBy(i => i.Region, i => i.Inventory); Elevated Formatting var allInventory = system.InventorySources .Select(src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }) .GroupBy( i => i.Region, i => i.Inventory); Block Formatting var allInventory = system.InventorySources .Select( src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }) .GroupBy( i => i.Region, i => i.Inventory ); List Formatting var allInventory = system.InventorySources .Select(src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }) .GroupBy(i => i.Region, i => i.Inventory); I want to come up with a standard for linq formatting so that it maximizes readability & understanding and looks clean and professional. So far I can't decide so I turn the question to the professionals here.

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  • Strangest LINQ to SQL case I have ever seen

    - by kubaw
    OK, so this is the strangest issue in .net programming I have ever seen. It seems that object fields are serialized in .net web services in order of field initialization. It all started with Flex not accepting SOAP response from .net web service. I have found out that it was due to the order of serialized fields was statisfying the order of fields in declared serializable class. It had something to do with generic lists and LINQ to SQL but I can't find out what. This one is really hard to reproduce. Example to get the idea: [Serializable] public class SomeSample { public int A; public int B; public int C; } I was querying some data tables within asmx web service using linq and returning list of SomeSample objects: var r = (from ...... select new SomeSample { A = 1, C = 3 }).ToList(); Now the list was once more iterated and B field was applied some value (ex. 2). However the returned soap envelope contained following excerpt: <A>1</A><C>3</C><B>2</B> Please notice the order of serialization. If I initially initialized all fields: var r = (from ...... select new SomeSample { A = 1, B = 2, C = 3 }).ToList(); object was serialized in correct order. I must add, that in both cases the debugger shows exactly the same content of "r" variable. Am I losing my mind or is this normal behavior? Thanks in advance.

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  • Searching a set of data with multiple terms using Linq

    - by Cj Anderson
    I'm in the process of moving from ADO.NET to Linq. The application is a directory search program to look people up. The users are allowed to type the search criteria into a single textbox. They can separate each term with a space, or wrap a phrase in quotes such as "park place" to indicate that it is one term. Behind the scenes the data comes from a XML file that has about 90,000 records in it and is about 65 megs. I load the data into a DataTable and then use the .Select method with a SQL query to perform the searches. The query I pass is built from the search terms the user passed. I split the string from the textbox into an array using a regular expression that will split everything into a separate element that has a space in it. However if there are quotes around a phrase, that becomes it's own element in the array. I then end up with a single dimension array with x number of elements, which I iterate over to build a long query. I then build the search expression below: query = query & _ "((userid LIKE '" & tempstr & "%') OR " & _ "(nickname LIKE '" & tempstr & "%') OR " & _ "(lastname LIKE '" & tempstr & "%') OR " & _ "(firstname LIKE '" & tempstr & "%') OR " & _ "(department LIKE '" & tempstr & "%') OR " & _ "(telephoneNumber LIKE '" & tempstr & "%') OR " & _ "(email LIKE '" & tempstr & "%') OR " & _ "(Office LIKE '" & tempstr & "%'))" Each term will have a set of the above query. If there is more than one term, I put an AND in between, and build another query like above with the next term. I'm not sure how to do this in Linq. So far, I've got the XML file loading correctly. I'm able to search it with specific criteria, but I'm not sure how to best implement the search over multiple terms. 'this works but far too simple to get the job done Dim results = From c In m_DataSet...<Users> _ Where c.<userid>.Value = "XXXX" _ Select c The above code also doesn't use the LIKE operator either. So partial matches don't work. It looks like what I'd want to use is the .Startswith but that appears to be only in Linq2SQL. Any guidance would be appreciated. I'm new to Linq, so I might be missing a simple way to do this. The XML file looks like so: <?xml version="1.0" standalone="yes"?> <theusers> <Users> <userid>person1</userid> <nickname></nickname> <lastname></lastname> <firstname></firstname> <department></department> <telephoneNumber></telephoneNumber> <email></email> </Users> <Users> <userid>person2</userid> <nickname></nickname> <lastname></lastname> <firstname></firstname> <department></department> <telephoneNumber></telephoneNumber> <email></email> </Users>

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  • Is linq more efficient than it appears on the surface?

    - by Justin984
    If I write something like this: var things = mythings .Where(x => x.IsSomeValue) .Where(y => y.IsSomeOtherValue) Is this the same as: var results1 = new List<Thing>(); foreach(var t in mythings) if(t.IsSomeValue) results1.Add(t); var results2 = new List<Thing>(); foreach(var t in results1) if(t.IsSomeOtherValue) results2.Add(t); Or is there some magic under the covers that works more like this: var results = new List<Thing>(); foreach(var t in mythings) if(t.IsSomeValue && t.IsSomeOtherValue) results.Add(t); Or is it something completely different altogether?

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  • NHibernate: Collection was modified; enumeration operation may not execute

    - by Daoming Yang
    Hi All, I'm currently struggling with this "Collection was modified; enumeration operation may not execute" issue. I have searched about this error message, and it's all related to the foreach statement. I do have the some foreach statements, but they are just simply representing the data. I did not using any remove or add inside the foreach statement. NOTE: The error randomly happens (about 4-5 times a day). The application is the MVC website. There are about 5 users operate this applications (about 150 orders a day). Could it be some another users modified the collection, and then occur this error? I have log4net setup and the settings can be found here Make sure that the controller has a parameterless public constructor I do have parameterless public constructor in AdminProductController Does anyone know why this happen and how to resolve this issue? A friend (Oskar) mentioned that "Theory: Maybe the problem is that your configuration and session factory is initialized on the first request after application restart. If a second request comes in before the first request is finished, maybe it will also try to initialize and then triggering this problem somehow." Many thanks. Daoming Here is the error message: System.InvalidOperationException Collection was modified; enumeration operation may not execute. System.InvalidOperationException: An error occurred when trying to create a controller of type 'WebController.Controllers.Admin.AdminProductController'. Make sure that the controller has a parameterless public constructor. --- System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. --- NHibernate.MappingException: Could not configure datastore from input stream DomainModel.Entities.Mappings.OrderProductVariant.hbm.xml --- System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.Collections.ArrayList.ArrayListEnumeratorSimple.MoveNext() at System.Xml.Schema.XmlSchemaSet.AddSchemaToSet(XmlSchema schema) at System.Xml.Schema.XmlSchemaSet.Add(String targetNamespace, XmlSchema schema) at System.Xml.Schema.XmlSchemaSet.Add(XmlSchema schema) at NHibernate.Cfg.Configuration.LoadMappingDocument(XmlReader hbmReader, String name) at NHibernate.Cfg.Configuration.AddInputStream(Stream xmlInputStream, String name) --- End of inner exception stack trace --- at NHibernate.Cfg.Configuration.LogAndThrow(Exception exception) at NHibernate.Cfg.Configuration.AddInputStream(Stream xmlInputStream, String name) at NHibernate.Cfg.Configuration.AddResource(String path, Assembly assembly) at NHibernate.Cfg.Configuration.AddAssembly(Assembly assembly) at DomainModel.RepositoryBase..ctor() at WebController.Controllers._baseController..ctor() at WebController.Controllers.Admin.AdminProductController..ctor() at System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) --- End of inner exception stack trace --- at System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) at System.Activator.CreateInstance(Type type, Boolean nonPublic) at System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) --- End of inner exception stack trace --- at System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) at System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) at System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) UPDATE CODE: In my Global.asax.cs, I'm doing this: protected void Application_BeginRequest(object sender, EventArgs e) { ManagedWebSessionContext.Bind(HttpContext.Current, SessionManager.SessionFactory.OpenSession()); } protected void Application_EndRequest(object sender, EventArgs e) { ISession session = ManagedWebSessionContext.Unbind(HttpContext.Current, SessionManager.SessionFactory); if (session != null) { try { if (session.Transaction != null && session.Transaction.IsActive) { session.Transaction.Rollback(); } else { session.Flush(); } } finally { session.Close(); } } } In the SessionManager class, I'm doing: public class SessionManager { private readonly ISessionFactory sessionFactory; public static ISessionFactory SessionFactory { get { return Instance.sessionFactory; } } private ISessionFactory GetSessionFactory() { return sessionFactory; } public static SessionManager Instance { get { return NestedSessionManager.sessionManager; } } public static ISession OpenSession() { return Instance.GetSessionFactory().OpenSession(); } public static ISession CurrentSession { get { return Instance.GetSessionFactory().GetCurrentSession(); } } private SessionManager() { Configuration config = new Configuration().Configure(); config.AddAssembly(Assembly.GetExecutingAssembly()); sessionFactory = config.BuildSessionFactory(); } class NestedSessionManager { internal static readonly SessionManager sessionManager = new SessionManager(); } } In the Repository, I'm doing this: public IEnumerable<User> GetAll() { ICriteria criteria = SessionManager.CurrentSession.CreateCriteria(typeof(User)); return criteria.List<User>(); } In the Controller, I'm doing this: public class UserController : _baseController { IUserRoleRepository _userRoleRepository; internal static readonly ILogger log = LogManager.GetLogger(typeof(UserController)); public UserController() { _userRoleRepository = new UserRoleRepository(); } public ActionResult UserList() { var myList = _usersRepository.GetAll(); return View(myList); } }

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